NR-12 is the Brazilian regulatory standard for safety in the use of machinery and equipment. It addresses the full lifecycle — design, protection devices, operation and maintenance — but maintenance is where energy control becomes critical: servicing a machine demands that every hazardous energy source be isolated and that the machine cannot restart while a worker is exposed.
NR-12 establishes technical references, principles and protective measures to guarantee the health and physical integrity of workers across the entire lifecycle of machines and equipment. It mandates protective systems, safety distances, command devices and — central to maintenance — procedures to isolate energy before anyone enters a danger zone.
For maintenance, inspection, cleaning or adjustment inside the danger zone, NR-12 requires that the machine be stopped and its energy sources isolated and locked out so it cannot be started. The principle mirrors LOTO: physical isolation, individual locks, and no possibility of restart while the work is underway and a worker is exposed.
NR-12 relies heavily on interlocked movable guards: opening a guard must remove power or stop the hazardous motion, and the machine must not restart merely because the guard is closed again. Defeating or bypassing safety devices is prohibited. Where a control system enforces these interlocks, its integrity becomes part of the safety case — and an unauthorized override must be impossible.
Stopping a machine is not the same as making it safe. Flywheels and rotating masses coast, pneumatic and hydraulic accumulators hold pressure, and gravity-loaded axes can fall. NR-12 maintenance procedures must account for residual movement and stored energy, restraining or dissipating it before the worker is exposed.
A safe restart requires deliberate, authorized action — never an automatic restoration of motion when power returns or a guard closes. NR-12 expects manual reset of the safety function and a controlled restart sequence. Binding restart authorization to an identified, authorized worker closes a gap that pure mechanical interlocks cannot.
NR-12 compliance is strengthened when every maintenance intervention, the energy-control state and the responsible worker are recorded. A digital platform that ties the lockout to the work order, enforces isolation before access and logs each step gives the documented, auditable maintenance history that NR-12 inspections and internal audits expect.
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